Obsolete.

XuInteger is the boxed representation which must be used in any context which only knows that it is dealing with a Position. XuInteger is a Heaper with all that implies. Specifically, one can take advantage of all the advantages of polymorphism (leading to uses by code that only knows it is dealing with a Position), but at the cost of representing each value by a heap allocated object to which pointers are passed. Such a representation is referred to as "boxed" because the pointer combined with the storage structure overhead of maintaining a heap allocated object constitutes a "box" between the user of the data (the guy holding onto the pointer), and the actual data (which is inside the Heaper).

See also IntegerVar.